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The key challenges in the design of datalinks for UAS systems compared to other wireless links is the long range of distances and speeds that need to be covered. The amount of spectrum available in the L-Band is not sufficient to support video applications common in UASs and so dual-band designs using both L-Band and C-Band are being considered. For L-Band, two projects funded by EUROCONTROL L-Band Digital Aeronautical Communications Systems 1 and 2 (L-DACS1 and L-DACS2) are often mentioned for use in UAS also. We briefly discuss issues with their use for UAS. Then we discuss several issues in UAS datalink design including availability, networking, preemption, and chaining. We also propose ways to mitigate interference with other systems in the L-Band.